SCM Repository

Revision 976

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Author:

george

Date:

Wed Nov 14 14:54:03 2001 UTC (18 years, 6 months ago)

Log Message:

Fix for a backpatching bug reported by Allen.
Because the boundary between short and long span-dependent
instructions is +/- 128, there are an astounding number of
span-dependent instructions whose size is over estimated.
Allen came up with the idea of letting the size of span
dependent instructions be non-monotonic, for a maxIter
number of times, after which the size must be monotonically
increasing.
This table shows the number of span-dependent instructions
whose size was over-estimated as a function of maxIter, for the
file Parse/parse/ml.grm.sml:
maxIter # of instructions:
10 687
20 438
30 198
40 0
In compiling the compiler, there is no significant difference in
compilation speed between maxIter=10 and maxIter=40. Actually,
my measurements showed that maxIter=40 was a tad faster than
maxIter=10! Also 96% of the files in the compiler reach a fix
point within 13 iterations, so fixing maxIter at 40, while high,
is okay.